User manual

45
Subject to change without notice
I n s t r u m e n t f u n c t i o n s
– MAX PEAK: In contrast to the auto peak detector this de-
tector will deliver only the maximum value of the spectrum
within a pixel of the curve (e.g. the measurement of pulsed
signals or frequency modulated signals).
– MIN PEAK: Delivers the minimum of a spectrum within a
pixel of the curve. Sine wave signals will be displayed with
their correct levels while noise-like signals will be sup-
pressed(e.g.forlteringsinewavesignalsfromnoise).
5.8 The use of markers
The HMS series offers several markers and delta markers
for the evaluation of curves. The markers are always tied to
the curve and indicate the frequency and the level at that. The
frequency position of the marker is marked by an arrow icon.
The nurmerical values of the frequency and the level are shown
as a “M” at the top of the screen. The unit of the level is the
same as the unit selected for the reference level.
The knob allows to choose up to 8 different markers. The indi-
vidual markers can be switched on and off with the respective
soft menu key. The soft menu key POSITION is used to set the
frequency position of the marker along the curve.
The delta marker level is always relative to the level of the
main marker (Marker 1), the unit of level is always dB. If a
marker is set to delta mode it is marked by a “D” in the read
out to distinguish it from a standard marker designated by a
leading “M”.
This button activates a submenu in which the active marker
can be set to the center frequency or the center frequency
can be set to the frequency of the active marker. Marker to
center (MKR TO CENT) allows to set the activated marker to
the center frequency. In contrast to marker to center allows
center to marker (CENT TO MKR) to set the center frequency
to an activated marker. A noise marker displays the noise at
the marker position.
The spectrum analyzer calculates the noise power density in
dBm/Hz from the trace pixel values, the selected resolution
bandwidth and the detector. Noise power density can provide
useful information when measurements are made on noise
or digitally modulated signals. However, valid results are ob-
tained only if the spectrum in the vicinity of the marker has a
flatfrequencyresponse.Thefunctiongivesincorrectresults
if measurements are made on discrete signals.
Noise marker mode is designated by a leading “N” in the
marker readout. Please note that the unit for the level mea-
surement switches from dBm to dBm/Hz. The noise marker
can switch on/off with a push on the softkey. The submenu
All Marker Off can be used to turn off all previous activated
markers simultaneously.
5.9 Peak-Search
The so called Peak-Search key will show the user the display of
the next maximum value. The button PEAK SEARCH activates
a menu which is used to detect peaks in the trace and assign
markers to them:
– PEAK: this function places the marker or the delta mar-
ker on the highest peak of the trace; the function acts on
the active marker, which is activated in the marker menu
before.
– NEXT PEAK: this function places the marker or the delta
marker relative to their current positions on the next lower
peak of the trace; the function acts on the active marker,
which is activated in the marker menu before.
– NEXT LEFT: this function places the marker or the delta
marker relative to their current positions on the next left
peak of the trace; the function acts on the active marker,
which is activated in the marker menu before.
– NEXT RIGHT: this function places the marker or the delta
marker relative to their current positions on the next right
peak of the trace; the function acts on the active marker,
which is activated in the marker menu before.
– MINIMUM: this function places the marker or the delta
marker on the lowest value of the trace; the function acts
on the active marker, which is activated in the marker menu
before.
5.10 Limit Lines
Limit lines are used to set limits for level characteristics
versus time or versus frequency on the display. They must
not be exceeded. For instance, the upper limits of permissible
spurious or harmonics of a DUT are marked by limit lines. In
the HMS series, the upper and lower limit value can be preset
by way of limit lines.
Pushing the button LINES will call the setting menu to set
limit lines. The softkey UPPER LIMIT activates / deactivates
the upper limit line which is displayed as a red line. After
activating the softkey UPPER POSITION the amplitude value
for the upper limit line can be set via the knob. The softkey
LOWER LIMIT activates / deactivates the lower limit line which
is displayed as a red line. After activating the softkey LOWER
POSITION the amplitude value for the lower limit line can be
set via the knob.
Additionally, the softkey BEEP activates an acoustic signal
which warns as soon as the trace leaves the amplitude range
denedbytheupperundlowerlimitline.ThesoftkeyMES-
SAGE activates a message in the upper left corner of the trace
display which shows if the whole trace is inside (pass/green)
or outside (fail/red) the amplituderangedenedbytheupper
and lower limit line.
5.11 Measure Menu
The button MEAS opens the measure menu with different op-
tions. The softkey CF > RX opens the receiver mode tuned to
the actual center frequency. The softkey M1 > RX opens the
receiver mode tuned to the actual frequency of marker 1.
5.12 Auto Tune
The AUTO TUNE button forces the HMS to perform a scan at
full span, locate the maximum peak value and center it in com-
bination with applicable RBW and span settings on the display.
The AUTO TUNE function is a comfort function to aid the
user. The closer the signal level is located to the general
noisefloor,theharderthepeak is detectable for the AUTO
TUNE algorithm. Therefore, it is possible that the settings
must be slightly adjusted by the user. This process can hold
up few seconds.